Anterior uveal spindle cell tumor in a cat

Purpose To describe a case of anterior uveal spindle cell tumor in a cat with features similar to spindle cell tumor of blue eyed dogs. Methods A 10‐year‐old female spayed domestic short‐haired cat was referred for an iris mass OS. The mass was solitary, nodular, nonpigmented, located medially, and causing dyscoria. A diagnosis of a benign epithelial tumor was suggested by a FNA of the mass. The cat was lost to follow‐up for 2 years, after which time she re‐presented with glaucoma, blindness and grossly evident iridal mass enlargement OS. Transconjunctival enucleation was performed and the globe submitted for histopathology. Results Histopathology of the enucleated globe revealed the superior iris to be infiltrated and effaced by a large population of neoplastic spindle cells. The cells were arranged in streams and bundles and exhibited Antoni‐A and Antoni‐B tissue patterns, which are characteristic of Schwann cell tumors. Mitotic figures were rare and cellular pleomorphism moderate. Immunohistochemical staining was positive for S‐100 protein and glial fibrillary acidic protein (GFAP), and negative for Melan‐A. Interestingly, there was no histological evidence of glaucoma. Conclusions Based on its histopathologic characteristics, this iris tumor was diagnosed as a Schwann cell variant of a peripheral nerve sheath tumor (PNST) closely resembling the spindle cell tumor of blue‐eyed dogs. Anterior uveal PNST has not been previously reported in cats to the authors’ knowledge. The presence of Antoni type A and type B tissue patterns along with immunohistochemical staining may facilitate a diagnosis of PNST and rule out malignant melanoma.     

Detection of Leishmania spp. and associated inflammation in ocular‐associated smooth and striated muscles in dogs with patent leishmaniosis

Objective Canine leishmaniosis is a disease characterized by the wide distribution of the parasite throughout the tissues of the host. The purpose of this study was to describe the presence of Leishmania spp. and associated inflammation in ocular‐associated muscles of dogs with patent leishmaniosis. Procedures Smooth muscles (iris dilator muscle, iris sphincter muscle, ciliary muscle, Müller muscle, smooth muscle of the periorbita and smooth muscle of the nictitating membrane) and striated muscles (orbicularis oculi muscle, obliquus dorsalis muscle and dorsal rectus muscle) were evaluated. Routine staining with hematoxylin and eosin and immunohistochemistry to detect Leishmania spp. were performed on tissue sections. Results Granulomatous inflammation was seen surrounding muscular fibers and was composed mainly of macrophages with scattered lymphocytes and plasma cells. This infiltrate could be seen in 52/473 (10.99%) samples of smooth muscle and 36/142 (25.35%) samples of striated muscle. Parasites were detected in 43/473 (9.09%) samples of smooth muscle and in 28/142 (19.71%) samples of striated muscle. Conclusions To the authors’ knowledge, this is the first report assessing the presence of Leishmania spp. and associated infiltrate in intraocular, extraocular and adnexal smooth and striated muscles. The inflammation present in those muscles could contribute to clinical signs already described, such as blepharitis, uveitis, and orbital cellulitis.     

Osseous metaplasia in the eye of a dog

Incisional iris biopsy was performed for diagnosis of an unusual opaque white mass protruding from the right ventrolateral iris of a 10-year-old neutered male Great Dane dog. Histopathology revealed a diagnosis of bone formation within otherwise normal iris tissue. No underlying etiology was identified. Osseous metaplasia or heterotopic bone formation may be an additional differential diagnosis for a nonneoplastic mass in the eye of a dog.     

Bilateral uveal metastasis of a subcutaneous fibrosarcoma in a cat

A 6‐year‐old neutered male domestic short‐haired cat was presented to the Comparative Ophthalmology service at Michigan State University with a 3‐week history of decreased appetite and redness of the left eye. The left forelimb had been removed 15 months previously because of the presence of a subcutaneous fibrosarcoma. In the left globe, a large iridal mass was associated with increased intraocular pressure and retinal detachment. A smaller mass involving the right iris was also present. Imaging revealed a 2‐cm mass in the left caudodorsal lung lobe, and abdominal ultrasound showed multifocal bilateral renal masses. Aspirates of these masses were nondiagnostic. The left globe was removed for palliative reasons, and histopathology showed that fibrosarcoma was infiltrating the iris, choroid, and optic nerve. Despite systemic chemotherapy with doxorubicin, the animal died 4 months after initial presentation. Histopathology confirmed highly angioinvasive metastatic fibrosarcoma also in the right uveal tract, the lungs, and both kidneys.     

Treatment of presumed iris melanoma in dogs by diode laser photocoagulation: 23 cases

A semiconductor diode laser was used to cause remission of isolated presumed iris melanoma in 23 dogs. All cases presented as unilateral areas of raised iris hyperpigmentation, ranging in size from 2× 3 mm to 4×12 mm. Cases were treated using a diode laser delivery system through either an operating microscope adapter (OMA) or a laser indirect ophthalmoscope (LIO) with a 20D lens. Laser treatment was delivered 'to effect' using power ranging from 80 to 1000 mW and cumulative durations up to 14 min, 31 s (14:31). Immediate shrinkage of the mass was noted following treatment. Five cases required more than one laser treatment with three eyes receiving two treatments and two eyes receiving three treatments. Follow-up from the last laser treatment ranged from 6 months to 4.5 years during which time the lesions exhibited no enlargement. Minor complications related to laser treatment were seen, including: dyscoria, iris hyperpigmentation, and corneal edema due to collateral hyperthermia. Glaucoma and cataract formation were not observed. Non-invasive diode laser photocoagulation appears to be a safe and effective method of treatment for isolated, pigmented iris masses in dogs.     

Gastric pleomorphic leiomyosarcoma in a Shetland sheepdog

A solitary mass of 6 x 6 x 5 cm was found in the smooth muscle layer of the pyloric part in the stomach of a Shetland sheepdog. The excised mass was solid, gray-white in color, and had central necrosis with hemorrhages. Microscopically, the neoplasm was composed of irregular bundles of spindle-shaped tumor cells and round tumor cells. A few multinucleated cells and gangliocyte-like cells were observed. The nuclei exhibited a high degree of atypia and many cells contained mitotic figures. Immunohistochemically, tumor cells were positive for vimentin and desmin, but negative for c-kit antibody. Ultrastructurally, tumor cells contained cytoplasmic myofilaments and pinocytotic vesicles. Based on these pathological findings, the tumor was diagnosed as gastric pleomorphic leiomyosarcoma.     

Anatomy of the California sea lion globe

Objective This study analyzed the morphology of the California sea lion globe to determine what features may contribute to their characteristic visual abilities. Procedure Globes from the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) collection were examined from gross photographs and microscopic sections stained with hematoxylin and eosin, trichrome, smooth muscle actin, and alcian blue periodic acid–Schiff (PAS). Transmission electron microscopy of the cornea and iris was also performed. Clinical results There was a round, flattened area ventromedial to the axial cornea. The pupil was tear‐drop shaped. Pectinate ligaments were visible without magnification. The retina was holangiotic, containing numerous spoke‐like venules and arterioles. The tapetum was green encompassing the entire fundus. The optic nerve was unmyelinated. Histological results The sclera was thinnest equatorially and thickest at the limbus and posterior pole. Bowman’s layer was difficult to see by light microscopy but clear with transmission electron microscopy. The cornea had a thick epithelium, thin endothelium and Descemet’s membrane, and the stroma thinned axially. The dilator muscle was absent near the pupil, but enlarged and mingled with the sphincter muscle near the iris base. A large, wide ciliary cleft with prominent trabeculae and a single continuous pectinate ligament was present. The corneoscleral trabecular meshwork was discontinuous. A round lens attached to the ciliary body via direct attachment to ciliary processes and delicate zonular ligaments. There was a circumferential muscle at the base of the ciliary processes. A thick tapetum covered the entire fundus except peripherally. The retina was characterized by sparse, large ganglion cells.     

Spontaneous deciduosarcoma in a domestic rabbit (Oryctolagus cuniculus)

Deciduosarcoma is a rare, hormonally dependent neoplasm with features of malignancy, previously reported only in rabbits enrolled in chronic toxicology studies involving estrogens with or without progestins. An exploratory laparotomy was performed on a 6-year-old pet Dutch dwarf rabbit following palpation of a 6-cm-diameter abdominal mass. Grossly, the mass was fleshy and nodular, adhered to but not appearing to originate from the small intestine, with a smaller mass of similar appearance involving the uterus, and an effaced mesenteric lymph node. Histologically, the mass was characterized by spindloid cells and large epithelioid cells with abundant pale eosinophilic vacuolated cytoplasm and an infiltrative pattern of growth. Giant cells with large, bizarre, hyperchromatic nuclei were common. Cells were positive by immunohistochemistry for vimentin and progesterone and estrogen receptors and negative for pancytokeratin (AE1/AE3), cytokeratin 18, desmin, alpha-smooth muscle actin (SMA), and CD10. Based on histologic and immunohistochemical findings, a diagnosis of deciduosarcoma was made.     

Mixed germ cell tumor in the eye of a dog.

A 3-year-old female neutered Staffordshire Bull Terrier presented with a mixed germ cell tumor involving the base of the iris and the ciliary body of the right eye. The tumor mass was composed primarily of packeted vacuolated, polygonal (hepatoid) cells and small round cells; epithelial cells lining tubuloacinar structures were a less prominent component. The hepatoid and round cells stained positively for alpha-fetoprotein and cytokeratin. The epithelial cells stained positively for cytokeratin only, and some contained cytoplasmic mucin droplets. The polygonal cells were interpreted as a hepatoid variant of yolk sac tumor, and the epithelial cells were considered a teratomatous component. Trabeculae of bone were observed within the mass and may have been metaplastic or a teratomatous element. Extragonadal germ cell tumors are rare in dogs and have previously been reported only in the suprasellar region. This is the first report of this tumor type in the eye of a nonhuman species.     

Undifferentiated tumor in the ovary of a corn snake (Elaphe guttata guttata)

A 6-year-old intact female corn snake (Elaphe guttata guttata) was presented with a 3-week history of anorexia. Coelomic radiographs revealed a 9 x 4 cm soft tissue opacity suggestive of a right ovarian enlargement. The mass (9 x 5 x 4 cm) was surgically removed, and multiple smears from tissue sections were stained with Diff-Quik. Multiple tissue samples from the mass were collected and fixed in formalin. Cytologic specimens were moderately cellular and contained light pink amorphous background material. The cells were primarily spindle-shaped with moderate to marked anisocytosis and anisokaryosis. Cells sometimes were round to polygonal, and rarely were arranged in small clusters. Macrophages occasionally were observed. Histologic specimens consisted of a highly cellular mass composed of pleomorphic, spindle-shaped cells and, occasionally, round to polygonal cells arranged in irregular fascicles. The neoplastic cells were immunoreactive for cytokeratin (AE1/AE3), smooth muscle actin, and skeletal muscle actin, but did not stain for vimentin or desmin. On the basis of the morphologic and immunohistochemical results, a diagnosis of ovarian undifferentiated carcinoma was made. In this report, we describe the challenges of using immunohistochemistry to diagnose this uncommon type of tumor in reptiles.     

A case of canine primitive neuroectodermal tumor (PNET)

A 2-year and 6 month-old, female, Golden Retriever showed circling behavior and seizure. By magnetic resonance imaging (MRI) examination, a mass was found on the surface of the left cerebral hemisphere, invading to the left temporal muscle. The skull bone between them was destroyed. The dog was euthanized and necropsied. Histologically, the mass contained a lot of undifferentiated anaplastic cells, forming Homer-Wright rosettes and pseudopalisading patterns. Thus, the case was diagnosed as primitive neuroectodermal tumor (PNET).     

Piloleiomyosarcoma in seven ferrets.

In each of seven ferrets (Mustela putorius furo) with leiomyosarcoma, a single dermal mass was identified and biopsied. Each mass consisted of a well-demarcated but nonencapsulated proliferation of large spindle- to strap-shaped cells arranged in interwoven bundles. The cells resembled the smooth muscle cells of the adjacent arrector pili muscles, but with marked nuclear pleomorphism. Immunohistochemical staining for smooth muscle actin, desmin, and vimentin was positive and staining for myoglobin and cytokeratin was negative. Follow-up on three of the ferrets indicates that the prognosis is good following complete surgical excision.     

Ocular manifestations of a metastatic adenocarcinoma in a horse

A 10‐year‐old German Warmblood gelding was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, for an iris mass OD, lethargy, intermittent fever, and coughing. Ophthalmic examination revealed a 7 × 9 mm raised, fleshy, whitish to pinkish, vascularized iris mass at the 2 o`clock position OD. Fundic examination showed multifocal round, brown to black, slightly raised lesions with indistinct margins and a surrounding hyperreflective zone OU. Physical examination revealed a temperature of 39.2 °C, sinus tachycardia, preputial and ventral edema, and an enlarged right mandibular lymph node. Results of a complete blood count and plasma biochemical profile showed mild anemia, leukocytosis, and thrombocytopenia. Severe splenopathy, moderate splenomegaly, and severe pulmonary pathology with nodules and large areas of consolidated lung parenchyma were observed on abdominal ultrasound and thoracic radiographs, respectively. Fine needle aspirates of the enlarged mandibular lymph node showed malignant epithelial neoplastic cells. The horse was euthanized because of the poor prognosis and subsequently underwent postmortem examination. Macroscopic necropsy and histopathology revealed an adenocarcinoma of suspected pulmonary origin with involvement of eyes, heart, liver, kidneys, spleen, diaphragm, skeletal muscles, mandibular, pulmonary, and internal iliac lymph nodes. Metastatic adenocarcinoma should be considered as a differential diagnosis in horses with iris masses, multifocal chorioretinal infiltrates, and clinical signs that conform to a paraneoplastic syndrome.     

Iridial melanocytoma in a ferruginous hawk (Buteo regalis): A case report and review of avian melanocytic neoplasia

A 21-year-old, suspected female captive ferruginous hawk (Buteo regalis) was followed for 3 years due to an iridial mass of the left eye (OS) that progressively increased in size. Enucleation of OS was eventually recommended due to the iridial mass taking up approximately 75% of the anterior chamber, and the bird seemed less active. A complete physical examination, complete blood cell count, biochemistry, and survey radiographs were performed pre-surgery with no findings indicating metastasis. A subconjunctival enucleation was performed and the globe was submitted for histopathology through the Comparative Ocular Pathology Lab of Wisconsin. The histopathologic evaluation determined the mass to be consistent with an iris melanocytoma, which has not been previously reported in this species. The patient recovered well from surgery and has remained comfortable and active for 117 days post-surgery. This case report aimed to review the current available information on avian ocular neoplasms as well as describe the clinical presentation, medical management and surgical procedure, and long-term follow-up for this patient to enhance clinical understanding of the behavior of iris melanocytic tumors in avian species.     

Immunohistochemical analysis of pseudorabies virus spread through neurons innervating the eyeball

Pseudorabies virus (PRV) was inoculated intraocularly into BALB/c mice, and the distribution pattern of cells positive for several neurotransmitters and viral antigens in the eyeball, trigeminal nerve ganglia, and superior cervical ganglia was examined immunohistochemically to clarify the neural route of the virus spread. In the eyeball, substance P (SP)- and calcitonin gene-related peptide (CGRP)-positive cells were detected in the ipsilateral iris and ciliary body, neuropeptide tyrosine (NPY)-positive cells were detected in the choloid membrane, and tyrosine hydroxylase (TH)-positive cells were detected in the ipsilateral inner nuclear layer of the retina; all these cells contained viral antigens. In the superior cervical ganglia, viral antigen-positive cells containing TH or NPY were found at bilateral sites. In the trigeminal nerve ganglia, viral antigen-positive cells containing SP or CGRP were found at bilateral sites. These findings indicated that the SP- and CGRP-positive ganglion cells of the trigeminal nerve ganglia innervating the iris or ciliary body, and the NPY-positive ganglion cells of the superior cervical ganglia innervating the iris, ciliary body, and choroid membrane served as the route for the virus spread. These findings also suggested that dopaminergic neurons, such as the TH-positive retinal cells and TH-positive ganglion cells of the superior cervical ganglia, served as the route for virus spread.     

Unilateral ocular subalbinism in a laboratory Beagle dog

Blue discoloration of the iris was found in the left eye of a male laboratory Beagle dog, which had a normal tricolor coat and clinically showed no visual impairment. Ophthalmoscopically, the affected eye revealed red-colored tigroid fundus, in which no tapetum was present. The retinal vasculature and the optic disc showed no noticeable changes. Histopathologically, in the left eye melanocytes had extremely few melanin granules in the anterior segment, including the anterior border layer, in the stroma and sphincter muscle of the iris and in the stroma of the ciliary body and choroid. However, the posterior pigment epithelium of the iris, the pigment epithelium of the ciliary body and the retinal pigment epithelium showed normal pigmentation. The tapetal elements were completely absent. Number and distribution of the S-100 protein-positive melanocytes with or without melanin granules in the iris, ciliary body and choroid of the left eye were similar to those of the normal right eye. Ultrastructurally, melanocytes in the anterior segment of the affected iris possessed no or few melanosomes which were incompletely melanized. In the right eye, no abnormal features were observed. Based on these results, the present case was diagnosed as unilateral ocular subalbinism with tapetal aplasia in a Beagle dog.     

A prostate fibromyxoid sarcoma with smooth muscle differentiation in a F344xBNF1 rat

This report describes a spontaneous prostate fibromyxoid sarcoma with smooth muscle differentiation in an approximately 136-week-old intact male F344xBNF1 rat on a diet study for 2 weeks. At necropsy, the prostate was markedly distorted and enlarged by a firm white multinodular mass (6.0 × 4.5 × 3.5 cm). Histopathologically, the mass consisted of solid sheets of interlacing mesenchymal spindle cells with indistinct cell borders. Nuclei were separated by variable amounts of hyaline to fibrillar eosinophilic and/or myxomatous material. The extracellular myxomatous material tended to form whorls and stained positively with alcian blue. The mass stained strongly with Masson trichrome and vimentin throughout. Approximately 5% of the neoplastic cells were positive for smooth muscle actin, and none stained for desmin and pancytokeratin. To the authors' knowledge, this fibromyxoid sarcoma with smooth muscle differentiation is the first such described prostatic sarcoma in a rat.     

Primary ureteral giant cell sarcoma in a Pomeranian

An 8-year-old male neutered Pomeranian dog was presented to the Veterinary Teaching Hospital at Oregon State University for surgical treatment of hydronephrosis of the left kidney and a left cranial abdominal mass. A primary ureteral mass was found during exploratory surgery, and the mass was resected and ureteral anastomosis was performed. Cytologic evaluation of the mass revealed 3 distinct cell populations, including a large number of multinucleated giant cells, a moderate number of thin spindle-shaped cells, and cohesive clusters of transitional epithelial cells. The cytologic diagnosis was giant cell sarcoma. The diagnosis was confirmed by histologic examination, and immunohistochemical staining was performed. The spindle-shaped cells and multinucleated giant cells were both immunoreactive for vimentin and spindle-shaped cells for S-100. Tumor cells did not express wide-spectrum cytokeratin, broad-spectrum muscle actin, smooth muscle actin, sarcomeric actin, desmin, BLA36, Mac 387, synaptophysin, neuron-specific enolase, glial fibrillary acid protein, or von Willebrand factor. These findings are most consistent with an anaplastic sarcoma with giant cells. This is the first case report of a primary ureteral giant cell sarcoma in a dog.